Anglo-German relations have been tested in the past 30 years by ministerial handbaggings, beef boycotts and tense penalty shootouts, yet the partnership between West Devon council and the Rhineland town of Wesseling seemed to have weathered every diplomatic crisis. Until now.

Twin towns since 1983, Wesseling and West Devon showed for almost three decades how school exchanges, football tournaments and the Okehampton Excelsior Silver Band's annual visit to the Wesseling town fair could build friendships and dispel prejudices. This year, a big joint anniversary party was meant to mark 30 years of shared history, but politicians in the German town found their British counterparts suddenly reluctant to commit.

"We wanted to mark the occasion, but are very conscious of how we spend council taxpayers' money," said the borough's councillor mayor, Mark Cann. In the end, all that 30 years of friendship boiled down to was a framed certificate and a "virtual ceremony" put up on YouTube. "It was a bit sad, really," said Joachim Scheffer, a politician from Wesseling.

The decline of the Wesseling-West Devon link is indicative of a wider neglect of the twin-town ideal. There are similar reports about British indifference from the twin-town schemes Herten-Doncaster, Lüneburg-Scunthorpe, Stuttgart-Cardiff, Bielefeld-Rochdale, Wetter-South Elmshall, Bönningstedt-Seaford and Salzgitter-Swindon.

Sven Giegold, a German Green MEP, who has been collecting these complaints, described the decline of twin towns as "an indictment of the depressing state of Anglo-German relations". "From talking to local councillors, I get the impression that twin-town and school-exchange links are being neglected because of a growing disinterest from the British side," he said. Giegold aims to make "the disintegration of a pan-European civil society" one of the campaigning issues for the 2014 European elections.

Few new partnerships are being created to replace those that have withered away. Figures shown to the Guardian by the European council of communities and regions show that while 74 new twin towns between Germany and Britain were created from 2000 to 2005, the last four years have only seen three new linkups.

Europe-wide austerity may be one of the reasons for the declining number of new partnerships, but it is twinnings between Britain and Germany in particular that are declining. 22 new partnerships were created between German and French towns from 2009 to 2013, 18 between Germany and Poland, and 17 between Germany and Italy.

In Wesseling, the linkup with the Brittany town of Pontivy is still thriving: "We still get a coachful of people coming from France every year. It's still very lively," said Friedhelm Weidenhaupt, who manages twinnings for the local council.

Some argue that in the age of Facebook and easyJet, the twin town idea has simply outlived its purpose. But many local politicians disagree. Claudia Leisse, a councillor from Duisburg-Rheinhausen, told the Guardian that twinning allowed her town to trade experience and knowhow with Sedgefield borough in County Durham.

"Two former mining areas struggling to cope with structural change, two towns blighted with youth unemployment, two former strongholds of the left – there was a lot we were able to learn from one another: for example, how to go about applying for regional funds from Brussels."

Five years ago, the link went dead: the Brits who had been most actively engaged in keeping the partnership alive had simply got too old. Too few British students were studying German to make school exchanges worthwhile.

"What we lost above all was a radically different perspective on things," said Leisse. "I've always found the British mentality a remedy for German angst: they put things into perspective that we obsess about, while still maintaining a love for values and traditions. You can't get that sort of life lesson from Facebook."

One of the oldest Anglo-German twin towns may also hold a glimpse of how the scheme could survive into the future. The partnership between Bristol and Hanover was declared in 1947, when resentment on both sides was still raw. Today there are regular artist exchanges, joint film projects for schools and reserved stalls at trade fairs in both cities.

Alix Hughes, who has a full-time job co-ordinating relations with Bristol's twins, said twinning was not just about tourism, but about building up long-term relationships. "It's worth remembering that Germany is still Britain's biggest trade partner. We shouldn't neglect a relationship as in-depth because it's easier to make brief acquaintances with the rest of the world online."